Chelidorhynx hypoxantha

The yellow-bellied fantail, or yellow-bellied fairy-fantail (Chelidorhynx hypoxanthus), is found in the Indian subcontinent, the Himalayas and parts of South-east Asia including Thailand, Vietnam and Myanmar, and is an altitudinal migrant. It is about 8 cm long, yellow below with a black eye-stripe, a white wing-bar and a broad black tail tipped white. It was once placed with the fantails but DNA analysis shows it to be a close relative of the fairy flycatcher, in the family Stenostiridae, and it often joins mixed flocks with leaf warblers, tits and black-faced warblers in winter. The source does not describe its status in China. (Wikipedia, general species account)